Preferred Reporting Items for Systematic

Moher et al. Systematic Reviews 2015, 4:1 http://www.systematicreviewsjournal.com/content/4/1/1

RESEARCH Open Access Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015 statement David Moher1*, Larissa Shamseer1, Mike Clarke2, Davina Ghersi3, Alessandro Liberatiˆ, Mark Petticrew4, Paul Shekelle5, Lesley A Stewart6 and PRISMA-P Group

Abstract Systematic reviews should build on a protocol that describes the rationale, hypothesis, and planned methods of the review; few reviews report whether a protocol exists. Detailed, well-described protocols can facilitate the understanding and appraisal of the review methods, as well as the detection of modifications to methods and selective reporting in completed reviews. We describe the development of a reporting guideline, the Preferred Reporting Items for Systematic reviews and Meta-Analyses for Protocols 2015 (PRISMA-P 2015). PRISMA-P consists of a 17-item checklist intended to facilitate the preparation and reporting of a robust protocol for the systematic review. Funders and those commissioning reviews might consider mandating the use of the checklist to facilitate the submission of relevant protocol information in funding applications. Similarly, peer reviewers and editors can use the guidance to gauge the completeness and transparency of a systematic review protocol submitted for publication in a journal or other medium.

Background and using data from primary research, since planning Systematic reviews are the reference standard for syn- provides an opportunity for the review team to antici- thesizing evidence in health care because of their meth- pate potential problems. When clearly reported proto- odological rigor. They are used to support the cols are made available, they enable readers to identify development of clinical practice guidelines and inform deviations from planned methods in completed reviews clinical decision-making. They are becoming increas- and whether they bias the interpretation of a review re- ingly common; in 2010, 11 new reviews were estimated sults and conclusions. Bias related to the selective to be published daily [1]. Ideally, systematic reviews are reporting of outcomes has been characterized as a ser- based on pre-defined eligibility criteria and conducted ious problem in clinical research, including systematic according to a pre-defined methodological approach as reviews [2-7]. outlined in an associated protocol. Until recently, systematic review protocols were gener- The preparation of a protocol is an essential compo- ally available only through select organizations, such as nent of the systematic review process; it ensures that a The Cochrane [8] and Campbell Collaborations and the systematic review is carefully planned and that what is Joanna Briggs Institute, for which the preparation of a planned is explicitly documented before the review protocol is mandatory. Outside of these organizations, starts, thus promoting consistent conduct by the review the existence of a protocol is infrequently reported in team, accountability, research integrity, and transparency completed reviews [9,10]. Fewer than half of 300 system- of the eventual completed review. A protocol may also atic reviews indexed on MEDLINE in November 2004 reduce arbitrariness in decision-making when extracting (most recent generalizable sample; 2014 update under- way) report working from a protocol [10], 80% of which * Correspondence: [email protected] are non-Cochrane affiliated. Of the non-Cochrane thera- ˆDeceased 1Ottawa Hospital Research Institute and University of Ottawa, Ottawa, peutic reviews, only 11% mentioned the existence of a Canada protocol [10]. The majority of reviews in health care are Full list of author information is available at the end of the article

© 2015 Moher et al.; licensee BioMed Central. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Moher et al. Systematic Reviews 2015, 4:1 Page 2 of 9 http://www.systematicreviewsjournal.com/content/4/1/1

conducted and published outside of Cochrane, however analyses of studies evaluating health care interventions [10]. The paucity of protocols may be due, in part, to the —the Preferred Reporting Items for Systematic reviews authors’ lack of knowledge about how to write them and and Meta-Analyses (PRISMA, www.prisma-statement. what to include. Currently, little succinct guidance is org) [12,13]—we have developed PRISMA for Protocols available for those preparing systematic review protocols, (PRISMA-P) 2014. Table 1 summarizes the difference although the recent Standards for Systematic Reviews in intentions between PRISMA-P and PROSPERO. prepared by the Institute of Medicine (IOM) provide The aim of PRISMA-P 2015 is to improve the quality some guidance toward addressing this gap [11]. of systematic review protocols, similar to the impact Many groups have called for the widespread preparation achieved by other reporting guidelines [18-20]. By help- and registration of systematic review protocols in order ing authors document an a priori road map of their sys- to increase the availability and accessibility of apriori tematic review, PRISMA-P also has the potential to methods for systematic reviews [12-14]. Such an effort improve the conduct of systematic reviews, as has been may reduce the duplication of effort [15] and reduce suggested of other reporting guidelines [21]. This State- the publication bias of systematic reviews. This chal- ment paper summarizes the development of the guide- lenge has been taken up by the Centre for Reviews and line and presents the PRISMA-P checklist. Dissemination, University of York, which has spearheaded the establishment of an international register—PROS- Terminology PERO (International Prospective Register of Ongoing There is no standard definition for a systematic review Systematic Reviews, http://www.crd.york.ac.uk/prospero) and meta-analysis protocol, and we note that some ter- [16,17]. The register, which enables the permanent docu- minology contained within these definitions may carry mentation of 22 mandatory (and 18 optional) items about different meanings for different readers (i.e., ‘systematic the a priori design and conduct of a review, was launched search’). The terms ‘systematic review’, ‘meta-analysis,’ in February 2011. At the time of writing, >5,000 system- and ‘protocol’ are defined in Table 2. The former two atic review protocols from over 70 countries have been terms are in accordance with the definitions reported in registered since its inception. Starting in October 2013, the PRISMA Statement [13] and are in line with those new Cochrane protocols were and continue to be auto- used by the Agency for Healthcare Research and Qual- matically added to PROSPERO. ity’s Evidence-based Practice Center (EPC) program [22], Along with the improved accessibility of protocols The Cochrane Collaboration [23], and the 2011 guidance through registration comes the need for strengthened from the Institute of Medicine [11]. The definition pro- transparency, accuracy, and completeness of the reports vided is a culmination of the terminology used by the of protocols intended for dissemination. A template to Standard Protocol Items: Recommendations for Inter- aid in the preparation of systematic review protocols, ventional Trials (SPIRIT) 2013 initiative [24], the PROS- such as a reporting guideline, may help achieve this. Fur- PERO register, and the IOM Standards (Table 2). thermore, such guidance will enable authors to create a clear and complete document of their a priori methods, Scope which may facilitate the registration of key information The PRISMA-P checklist is intended primarily for the into the PROSPERO database. Building on an estab- preparation of protocols of systematic reviews and meta- lished guideline for systematic reviews and meta- analyses that summarize aggregate data from studies,

Table 1 PROSPERO and PRISMA-P Definition and objective PROSPERO: International Prospective An online portal through which to register the intention to conduct a systematic review, with health-related Register of Systematic Reviews outcomes, before it is initiated [16]. One of the main goals of PROSPERO is to make the intent of systematic reviews known before they are conducted in order to reduce the unplanned duplication of systematic reviews [15]. In addition, by requiring the documentation of a priori methods, the register facilitates increased transparency in the review process by allowing readers of systematic reviews to compare methods, outcomes, and analyses carried out with those planned in advance and judge whether such changes impact the results of a review. PRISMA-P: Preferred Reporting Items for A guideline to help authors prepare protocols for planned systematic reviews and meta-analyses that Systematic Review and Meta-Analysis provides them with a minimum set of items to be included in the protocol. A protocol is intended to Protocols provide the rationale for the review and pre-planned methodological and analytic approach, prior to embarking on a review. Investigators should prepare a review protocol in advance of registering it in PROSPERO so that details requiring further consideration may be thought through in advance, avoiding the need for multiple amendments to registration information. PRISMA-P items have been derived largely from the PRISMA checklist and items of the PROSPERO register, in order to facilitate seamless registration. Moher et al. Systematic Reviews 2015, 4:1 Page 3 of 9 http://www.systematicreviewsjournal.com/content/4/1/1

Table 2 PRISMA-P terminology Term Definition Systematic A systematic review attempts to collate all relevant evidences that fits pre-specified eligibility criteria to answer a specific research review question. It uses explicit, systematic methods to minimize bias in the identification, selection, synthesis, and summary of studies. When done well, this provides reliable findings from which conclusions can be drawn and decisions made [25,26]. The key characteristics of a systematic review are (a) a clearly stated set of objectives with an explicit, reproducible methodology; (b) a systematic search that attempts to identify all studies that would meet the eligibility criteria; (c) an assessment of the validity of the findings of the included studies (e.g., assessment of risk of bias and confidence in cumulative estimates); and (d) systematic presentation, and synthesis, of the characteristics and findings of the included studies Meta-analysis Meta-analysis is the use of statistical techniques to combine and summarize the results of multiple studies; they may or may be contained within a systematic review. By combining data from several studies, meta-analyses can provide more precise estimates of the effects of health care than those derived from the individual studies Protocol In the context of systematic reviews and meta-analyses, a protocol is a document that presents an explicit plan for a systematic review. The protocol details the rationale and a priori methodological and analytical approach of the review particularly the evaluations of the effects of interven- Pre-meeting activities tions. There are many review types that are outside of In developing the PRISMA-P checklist, the steering this scope. As such, given the general lack of protocol committee compiled a list of items from various tools guidance for other types of reviews, we encourage re- relating to the preparation of systematic review proto- viewers preparing any type of review protocol to make cols for discussion at a consensus meeting of experts. use of PRISMA-P as applicable. Readers can also use the Specifically, we mapped items from a Delphi exercise checklist to assess the completeness of the reporting of carried out during the development of PROSPERO [28], published protocols. However, it is not recommended to PROSPERO register items, PRISMA checklist items [13], use the checklist as an assessment tool to gauge the ap- SPIRIT 2013 checklist items [29], and items of IOM propriateness of the methods of a systematic review Standard 2.6 [11] against each other to identify unique protocol; it has not been validated for that purpose. and overlapping concepts. Lessons learned from the development of the SPIRIT checklist with respect to the concept and content of research protocols were used to Development of PRISMA-P 2015 guide discussion and debate at the meeting. An international steering committee (MC, DG, AL, DM, MP, PS, and LAS) comprising members with wide-ranging PRISMA-P consensus meeting experience in systematic review methodology, protocol Twenty-three international experts attended the registry development, and reporting guideline development PRISMA-P consensus meeting on June 23–24, 2011, in led the development of PRISMA-P, coordinated by LS. The Rockville, MD, USA to gain consensus on and reduce process proposed by the Enhancing the Quality and Trans- the number of potential PRISMA-P items. Delegates in- parency of Health Research (EQUATOR) Network was cluded journal editors, systematic review methodologists used to guide PRISMA-P development [27]. The process (including directors and representatives from inter- has 18 step-by-step recommendations grouped into five national Cochrane Centres, Agency for Healthcare Re- main stages: search and Quality’s (AHRQ’s) Evidence-based Practice Centres, and the UK National Institute for Health Re- 1. Initial steps (determine the need for a reporting search), reporting guideline developers, information spe- guideline); cialists, biostatisticians, and health research funders. 2. Pre-meeting activities (identify contributors, conduct Through group discussion at the meeting, 38 potential Delphi exercise, generate a list of potential items, checklist items were reduced to 22. and prepare for face-to-face meeting); 3. Face-to-face consensus meeting (present results of pre-meeting activities and relevant evidence); Post-meeting activities 4. Post-meeting activities (develop guidance Statement, Following the meeting, the steering committee revised Explanation and Elaboration document, and a the draft 22-item checklist and refined their wording publication strategy); such that they accurately reflected meeting discussions. 5. Post-publication activities (encourage uptake of The draft checklist was also presented to the PROS- guideline). PERO group, at a scientific meeting of the Cochrane Collaboration, for input and feedback and to AHRQ’s The first stage, ‘Initial steps,’ was described above; de- Learning Network. After each of these reviews, the steer- tails of the remaining four steps are below. ing committee made minor amendments to the items. Moher et al. Systematic Reviews 2015, 4:1 Page 4 of 9 http://www.systematicreviewsjournal.com/content/4/1/1

The checklist was then circulated to all meeting invitees freely available on the websites of the PRISMA Group for critical input. (www.prisma-statement.org) and EQUATOR Network (www.equator-network.org). The PROSPERO register The PRISMA-P 2015 checklist also contains a link to the guidance to encourage regis- The final PRISMA-P 2015 checklist contains 17 numbered trants to prepare a complete documentation of their items (26 including sub-items) Items are categorized into protocol if they have not done so already. three main sections: administrative information, introduc- We plan to develop an educational webinar about the tion, and methods (Table 3). rationale, usefulness, and potential impact of PRISMA-P, We made a conscious effort to harmonize the PRISMA- similar to what was done for PRISMA [31]. In addition, P checklist items with the items of the PRISMA checklist the potential for PRISMA-P 2015 to be used as an educa- to facilitate authors in transitioning their protocol into tional tool for authors, peer reviewers, and editors will be a report of a systematic review. Thirteen PRISMA-P explored. Targeted implementation activities for PRISMA- sub-items have existing PRISMA counterparts. Where P will be developed in a systematic manner together with PRISMAwordingorcontentdidnotsufficientlyad- experts in knowledge translation. The PRISMA website dress protocol reporting, checklist items were modified. and social media (@PRISMAStatement, www.twitter. Readers familiar with PRISMA will notice that PRISMA- com/PRISMAStatement) will be used to make an- P does not contain a flow diagram documenting the flow nouncements about the launch of PRISMA-P and edu- of studies throughout the systematic review process. Such cational initiatives. documentation is possible only after a review has been carried out and remains an essential component to include in Endorsement the report of a completed systematic review or meta- We encourage journals publishing systematic review prod- analysis; for further guidance, see the PRISMA Explanation ucts to modify their ‘Instructions for Authors’ section to and Elaboration document [12]. endorse PRISMA-P 2015 and to consider publishing sys- We strongly recommend that the present document tematic review protocols, if they do not do so already. We and the accompanying PRISMA-P 2015 Explanation and plan to communicate with known endorsers of PRISMA Elaboration document [30], which includes examples of (http://prisma-statement.org/endorsers.htm) as well as to good reporting, rationale, and evidence (where available), other, relevant non-endorsing journals, to ask them to be read together with the PRISMA-P 2015 checklist. consider extending their support to PRISMA-P. To help ensure optimal uptake by systematic reviewers, PRISMA-P 2015 explanation and elaboration we propose a uniform endorsement policy across organi- Once the steering committee prepared the PRISMA-P zations and journals involved in the development and 2015 Statement and checklist, they drafted the content publication of systematic review protocols, demonstrated of an Explanation and Elaboration document, with as- by the adoption of the following statement: sistance from the larger PRISMA-P group. The explana- tory text was derived largely from discussions at the ‘[this organization/journal] requires a completed PRISMA-P meeting (recorded at the time) as well as the PRISMA-P 2015 checklist as a condition of submission PRISMA Explanation and Elaboration document [12]. of systematic review protocols. We recommend that, Examples of well-reported PRISMA-P items came from while completing the PRISMA-P 2015 checklist, you protocols registered in the PROSPERO database, ensure your protocol addresses all items. Taking the AHRQ’s EPC Program, and the Cochrane Database of time to ensure that your protocol adheres to these Systematic Reviews or those published elsewhere. After basic reporting elements will improve your manuscript the entire group had an opportunity to suggest addi- and potentially enhance its chances of eventual tions, deletions, and changes, the steering committee acceptance.’ combined all amendments to create the PRISMA-P 2014 Explanation and Elaboration document [30]. Such a statement could be included in a journal’s ‘In- structions to Authors,’ or for funding agencies and those Post-publication activities commissioning systematic reviews, in their Application The post-publication activities recommended by EQUA- Guidelines, recommending that applicants developing TOR include seeking and responding to criticism, encour- the proposals of systematic reviews for funding use aging the endorsement of and adherence to the guideline PRISMA-P 2014. Peer reviewers and scientific commit- from various stakeholders, translating the guideline into tees can also use the checklist to gauge the extent to other languages, evaluating its impact, ensuring website which protocols include necessary information. development, and updating of the guideline. The As has been done for previous reporting guidelines PRISMA-P 2015 checklist and related publications are [18,32] we plan to evaluate whether and to what degree Moher et al. 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Table 3 PRISMA-P 2015 checklist: recommended items to include in a systematic review protocola Section/topic Item # Checklist item ADMINISTRATIVE INFORMATION Title Identification 1a Identify the report as a protocol of a systematic review Update 1b If the protocol is for an update of a previous systematic review, identify as such Registration 2 If registered, provide the name of the registry (e.g., PROSPERO) and registration number Authors Contact 3a Provide name, institutional affiliation, and e-mail address of all protocol authors; provide physical mailing address of corresponding author Contributions 3b Describe contributions of protocol authors and identify the guarantor of the review Amendments 4 If the protocol represents an amendment of a previously completed or published protocol, identify as such and list changes; otherwise, state plan for documenting important protocol amendments Support Sources 5a Indicate sources of financial or other support for the review Sponsor 5b Provide name for the review funder and/or sponsor Role of sponsor/ 5c Describe roles of funder(s), sponsor(s), and/or institution(s), if any, in developing the protocol funder INTRODUCTION Rationale 6 Describe the rationale for the review in the context of what is already known Objectives 7 Provide an explicit statement of the question(s) the review will address with reference to participants, interventions, comparators, and outcomes (PICO) METHODS Eligibility criteria 8 Specify the study characteristics (e.g., PICO, study design, setting, time frame) and report characteristics (e.g., years considered, language, publication status) to be used as criteria for eligibility for the review Information sources 9 Describe all intended information sources (e.g., electronic databases, contact with study authors, trial registers, or other grey literature sources) with planned dates of coverage Search strategy 10 Present draft of search strategy to be used for at least one electronic database, including planned limits, such that it could be repeated Study records Data management 11a Describe the mechanism(s) that will be used to manage records and data throughout the review Selection process 11b State the process that will be used for selecting studies (e.g., two independent reviewers) through each phase of the review (i.e., screening, eligibility, and inclusion in meta-analysis) Data collection process 11c Describe planned method of extracting data from reports (e.g., piloting forms, done independently, in duplicate), any processes for obtaining and confirming data from investigators Data items 12 List and define all variables for which data will be sought (e.g., PICO items, funding sources), any pre-planned data assumptions and simplifications Outcomes and 13 List and define all outcomes for which data will be sought, including prioritization of main and prioritization additional outcomes, with rationale Risk of bias in 14 Describe anticipated methods for assessing risk of bias of individual studies, including whether this will individual studies be done at the outcome or study level, or both; state how this information will be used in data synthesis Data Synthesis 15a Describe criteria under which study data will be quantitatively synthesized 15b If data are appropriate for quantitative synthesis, describe planned summary measures, methods of handling data, and methods of combining data from studies, including any planned exploration of consistency (e.g., I2, Kendall’s tau) 15c Describe any proposed additional analyses (e.g., sensitivity or subgroup analyses, meta-regression) 15d If quantitative synthesis is not appropriate, describe the type of summary planned Moher et al. Systematic Reviews 2015, 4:1 Page 6 of 9 http://www.systematicreviewsjournal.com/content/4/1/1

Table 3 PRISMA-P 2015 checklist: recommended items to include in a systematic review protocola (Continued) Meta-bias(es) 16 Specify any planned assessment of meta-bias(es) (e.g., publication bias across studies, selective reporting within studies) Confidence in 17 Describe how the strength of the body of evidence will be assessed (e.g., GRADE) cumulative evidence PRISMA-P Preferred Reporting Items for Systematic review and Meta-Analysis Protocols. aIt is strongly recommended that this checklist be read in conjunction with the PRISMA-P Explanation and Elaboration [30] for important clarification on the items. Amendments to a review protocol should be tracked and dated. The copyright for PRISMA-P (including checklist) is held by the PRISMA-P Group and is distributed under a Creative Commons Attribution License 4.0. endorsement of PRISMA-P 2015 by journals (and poten- Implementation tially by other organizations) influences the complete- The current system of implementing reporting guide- ness of reported protocols. Such an evaluation will be lines is not optimal. At present, their primary mechan- planned after allowing sufficient time for the wide dis- ism of uptake is through endorsement by journals at semination of PRISMA-P 2015. their discretion, if at all. In journals that do endorse

Table 4 Proposed stakeholders, actions, and potential benefits for supporting adherence to PRISMA-P Stakeholder Proposed action Potential benefits Funders Promote or mandate adherence to PRISMA-P or use PRISMA-P as Improved quality, completeness, and consistency a template for systematic review proposals for grant applications of systematic review proposal submissions Standardized protocol content will improve peer review efficiency and investigator understanding of requirements Systematic review authors/ Use/adhere to PRISMA-P during protocol development Improved quality, completeness, and consistency groups/organizations of protocol content Enables reviewers to anticipate and avoid future changes to review methods (i.e., outcomes) Increased awareness of minimum content for protocol reporting Improved completeness of reporting of completed reviews PROSPERO (and other Encourage the development of PRISMA-P-based protocols Improved quality of registry entries review registries) Improved consistency across registry entries, protocols, and systematic reviews Practice guideline Use PRISMA-P to gauge the completeness of protocols and Enables easy comparison across protocols, registry developers facilitate detection of selective reporting when considering entries, and completed systematic reviews reviews for guideline inclusion Policymakers Advocate use of PRISMA-P by those funding and carrying May yield better quality, more complete, and more out systematic reviews consistent reviews to inform decision-making Journal editors Encourage compliance to PRISMA-P for authors submitting Improved quality, completeness, and consistency protocols for publication of protocols over those published in journals not endorsing PRISMA-P Offer PRISMA-P as a template to assist in protocol Increased efficiency in protocol peer and writing for publication author understanding of journal requirements Improved transparency and interpretation of reviews by readers Educators Use PRISMA-P as a training tool Simplified teaching and grading of protocols Encourage adherence in students submitting protocols Improved quality, completeness, and for coursework consistency of protocol content Students Develop protocols for coursework or research using PRISMA-P Improved understanding of the minimum protocol content Well-trained systematic reviewer going into the workforce Moher et al. Systematic Reviews 2015, 4:1 Page 7 of 9 http://www.systematicreviewsjournal.com/content/4/1/1

guidelines, language describing their support is often described reasons for the change in the completed review vague, leaving authors unclear on what they are sup- [3]. Discrepant outcomes added or upgraded from second- posed to do with a given reporting guideline during the ary to primary at the review stage were more likely to be submission process [33]. Furthermore, policies around statistically significant than those outcomes that had not how journal editors and peer reviewers should ensure changed. This practice (i.e., including, excluding, or chan- and/or enforce adherence to reporting checklists are ging outcomes in association with the strength or direc- even less clear, if they exist at all [34]. Other barriers to tion of findings) has the potential to bias the findings of implementation may include a lack of awareness of the any meta-analysis and the review’s conclusions. As review guideline and perceived burden of using a reporting protocols are expected to become increasingly available guideline checklist during the editorial process [35]. with the advent of PROSPERO, clear reporting will be- Some well-known checklists, such as PRISMA, include come essential to facilitate the identification of discrepan- a column to the right of the main checklists in which cies between protocol and review by readers and help users report the page number on which a specific item is them determine whether they need to be cautious in inter- reported. This was initially intended to help authors en- preting findings. sure each checklist item is addressed and to aid peer re- Reporting and publishing protocols is an important step viewers in locating reported text for each item within a in increasing the transparency of the research process and document. However, this system is not optimal. One reliability of published papers. For example, some journals major problem is that peer reviewers still have to search require a copy of the protocol as part of the peer review within a considerable body of text to locate the exact process of randomized trials. As of 1 March 2014, BioMed text describing a checklist item. When multiple items Central has published 4,158 trial protocols across 66 of its are listed separately but reported together or vice versa, 258 open-access journals, including 1,026 in Trials. Sys- this problem is compounded, because exactly which tematic Reviews, a BioMed Central journal launched in content pertains to each item may remain unclear. February 2012, is committed to publishing systematic re- The lack of implementation and adherence to report- view products, including protocols [41], and has published ing guidelines is systemic; additional authorities encoun- 142 protocols since inception (to 8 June 2014). tered early in the research process should promote a Journals, granting agencies, and systematic review or- clearer message about author adherence to reporting ganizations are encouraged to endorse PRISMA-P 2015 standards if improvements in reporting are to be made. in their ‘Instructions to Authors’ and guidance for appli- In targeting protocols of systematic reviews, PRISMA-P cants and to implement its use during their peer review has a unique opportunity to not only affect the way in process of systematic review proposals. Reviewers are which protocols are reported but to also impact the way encouraged to use the PRISMA-P checklist and Explan- in which reviews are eventually conducted, perhaps ation and Elaboration [30] document to guide them allowing for a more seamless transition into a com- through the documentation of a protocol. Doing so will pletely reported systematic review. enhance the completeness of reporting of review proto- To overcome known challenges with reporting guideline cols, facilitate the assessment of potential in systematic uptake [36,37], we are developing a prospective imple- reviews, and hopefully strengthen the methodological mentation strategy for PRISMA-P 2015 using knowledge quality and reliability of completed systematic reviews. translation principles involving theoretically derived interventions [37] which have demonstrated effectiveness in Competing interests The PRISMA-P 2015 initiative was supported by the AHRQ, USA (Contract No. the development of implementation interventions for clin- HHSA 290 2007 10059 I) and the Canadian Institutes for Health Research ical practice guidelines [38,39]. An initial list of proposed (Reference No. 114369). This manuscript does not reflect the opinions of stakeholders who can assist in the implementation of either agency; one author, SC, is an employee of AHRQ. MC, DG, DM, MP, and LAS are members of the Advisory Board for PROSPERO. DGA, SC, MC, PRISMA-P, along with proposed actions and benefits, is JG, MH, JM, and MP are members of the Editorial Board, and DM, PS, and provided in Table 4. LAS are co-Editors in Chief of Systematic Reviews. None of the authors who are editors of Systematic Reviews were involved in the handling of this paper or the decision to publish it. Discussion Studies comparing trial protocols to final reports have Authors’ contributions widely documented both the presence and the extent of DM, LS, MC, DG, AL, MP, PS, and LAS conceived this paper. DM and LS drafted the article, and all authors critically revised it for important reporting biases in publications of randomized trials intellectual content. All authors approved the final version of this article. DM [2,40]. Protocols for systematic reviews are rarely available is the guarantor of this work. for such comparisons, with the exception of select organizations. Of 288 reviews with available protocols in a 2006/ Acknowledgements The PRISMA-P steering committee would like to thank the following staff 2007 cohort, 64 (22%) were observed to have at least one from the Ottawa Hospital Research Institute (OHRI): Jodi Peters for her efforts discrepant outcome with their completed reviews; only 4 organizing the PRISMA-P consensus meeting, Michael Zhao for his assistance Moher et al. Systematic Reviews 2015, 4:1 Page 8 of 9 http://www.systematicreviewsjournal.com/content/4/1/1

in preparing documents for the PRISMA-P meeting, Dr. Mohammed Ansari 5. Dwan K, Gamble C, Williamson PR, Kirkham JJ, Reporting Bias Group: for valuable input and feedback throughout the process, and Justin Thielman Systematic review of the empirical evidence of study publication bias for his assistance during the preparation of the PRISMA-P manuscripts. and outcome reporting bias—an updated review. PLoS ONE 2013, 8(7):e66844. 6. Norris SL, Holmer HK, Ogden LA, Fu R, Abou-Setta AM, Viswanathan MS, Dedication McPheeters ML: Selective Outcome Reporting as a Source of Bias in Reviews of The PRISMA-P 2015 initiative is dedicated to our colleague Alessandro Liberati Comparative Effectiveness (Prepared by the Oregon Evidence-Based Practice Center (1954–2012) who passed away during the time in which PRISMA-P 2015 was Under Contract no. 290-2007-10057-I). Rockville: Agency for Healthcare Research under development and whose contributions to this work were invaluable. and Quality; 2012. 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